i have 2 plecos in my tank 1 14in. 1 12in. the larger one is very finicky and does not like bottom feeder food from stores very seldom on driftwood either but is very healthy have no algae in tank either and it killed a 20in. clown knivefish about a year 6 mo. ago but has never bothered any other fish in tank just that 1 and was noradic about doing so. any suggestions on feeding?